一、Flowable简介

1. Flowable是什么

Flowable是一个使用Java编写的轻量级业务流程引擎。Flowable流程引擎可用于部署BPMN 2.0流程定义（用于定义流程的行业XML标准）， 创建这些流程定义的流程实例，进行查询，访问运行中或历史的流程实例与相关数据，等等。

2. Flowable与Activiti

Flowable项目源自于Activiti，通过两个框架的发展史即知。在2016.7~2017.5期间Activiti团队内部已经产生了重大的分歧，于是原班核心人员（Activiti5以及6比较核心的leader）Tijs Rademakers和Joram Barrez等便去开发Flowable框架了，原来的Activiti6以及Activiti5代码则留给 Salaboy团队进行开发和维护。Flowable是基于Activiti-6.0.0.Beta4分支开发的。目前Flowable已经修复了Activiti6很多的bug，可以实现零成本从Activiti迁移到Flowable。

Flowable与Activiti

二、第一个应用

1. Spring Boot 整合 Flowable

Spring Boot 提倡约定大于配置。要开始工作，只需在项目中添加flowable-spring-boot-starter依赖，另外Flowable还需要数据库来存储数据。我这里使用mysql + jpa，当然也可以使用H2数据库或者其他数据库。maven配置：

      <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.flowable</groupId>
            <artifactId>flowable-spring-boot-starter</artifactId>
            <version>6.6.0</version>
        </dependency>

接下来创建对应的数据库，配置数据源：

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/flowable?serverTimezone=Asia/Shanghai&allowMultiQueries=true&useUnicode=true&characterEncoding=UTF-8
    username: root
    password: 123456
    driver-class-name: com.mysql.cj.jdbc.Driver
  jpa:
    properties:
      hibernate:
        hbm2ddl:
          auto: update
        dialect: org.hibernate.dialect.MySQL5InnoDBDialect
    open-in-view: true

以上步骤就是最简单的整合方法了。
运行项目，Flowable创建一系列的数据库表（对应表的用途说明请看文末附件），那就代表整合成功了。

2. 部署流程模型

这里用学生请假流程做例子，首先由学生发起请假申请，然后由老师进行审核，老师审核结束后进行判断：
1.如果请假天数大于2天，流转到校长处审核，然后流程结束。
2.如果请假天数不大于2天，流程结束。

部署流程需要一个.bpmn20.xml文件，可用手动编辑，也可以借助一些工具创建Flowable ModelerFlowable 提供的Web模型编辑工具、Eclipse IDE 插件等等

<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:flowable="http://flowable.org/bpmn" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:omgdc="http://www.omg.org/spec/DD/20100524/DC" xmlns:omgdi="http://www.omg.org/spec/DD/20100524/DI" typeLanguage="http://www.w3.org/2001/XMLSchema" expressionLanguage="http://www.w3.org/1999/XPath" targetNamespace="http://www.flowable.org/processdef">
  <process id="StudentLeave" name="学生请假流程" isExecutable="true">
    <startEvent id="start" name="开始" flowable:formFieldValidation="true"></startEvent>
    <userTask id="apply" name="请假申请" flowable:assignee="${studentUser}" flowable:formFieldValidation="true">
      <extensionElements>
        <modeler:initiator-can-complete xmlns:modeler="http://flowable.org/modeler"><![CDATA[false]]></modeler:initiator-can-complete>
      </extensionElements>
    </userTask>
    <userTask id="teacherPass" name="老师审批" flowable:candidateGroups="teacher" flowable:formFieldValidation="true"></userTask>
    <exclusiveGateway id="judgeTask" name="判断是否大于2天"></exclusiveGateway>
    <endEvent id="end" name="结束"></endEvent>
    <userTask id="principalPass" name="校长审批" flowable:candidateGroups="principal" flowable:formFieldValidation="true"></userTask>
    <sequenceFlow id="principalCheck" name="通过" sourceRef="principalPass" targetRef="end">
      <conditionExpression xsi:type="tFormalExpression"><![CDATA[${outcome=='通过'}]]></conditionExpression>
    </sequenceFlow>
    <sequenceFlow id="principalNotPassFlow" name="驳回" sourceRef="principalPass" targetRef="apply">
      <conditionExpression xsi:type="tFormalExpression"><![CDATA[${outcome=='驳回'}]]></conditionExpression>
    </sequenceFlow>
    <sequenceFlow id="teacherPassFlow" name="通过" sourceRef="teacherPass" targetRef="judgeTask">
      <conditionExpression xsi:type="tFormalExpression"><![CDATA[${outcome=='通过'}]]></conditionExpression>
    </sequenceFlow>
    <sequenceFlow id="teacherNotPassFlow" name="驳回" sourceRef="teacherPass" targetRef="apply">
      <conditionExpression xsi:type="tFormalExpression"><![CDATA[${outcome=='驳回'}]]></conditionExpression>
    </sequenceFlow>
    <sequenceFlow id="startFlow" sourceRef="start" name="流程开始" targetRef="apply"></sequenceFlow>
    <sequenceFlow id="applyFlow" sourceRef="apply" name="申请流程" targetRef="teacherPass"></sequenceFlow>
    <sequenceFlow id="judgeLess" name="小于2天" sourceRef="judgeTask" targetRef="end">
      <conditionExpression xsi:type="tFormalExpression"><![CDATA[${day <= 2}]]></conditionExpression>
    </sequenceFlow>
    <sequenceFlow id="judgeMore" name="大于2天" sourceRef="judgeTask" targetRef="principalPass">
      <conditionExpression xsi:type="tFormalExpression"><![CDATA[${day > 2}]]></conditionExpression>
    </sequenceFlow>
  </process>
  <bpmndi:BPMNDiagram id="BPMNDiagram_StudentLeave">
    <bpmndi:BPMNPlane bpmnElement="StudentLeave" id="BPMNPlane_StudentLeave">
      <bpmndi:BPMNShape bpmnElement="start" id="BPMNShape_start">
        <omgdc:Bounds height="30.0" width="30.0" x="100.0" y="163.0"></omgdc:Bounds>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape bpmnElement="apply" id="BPMNShape_apply">
        <omgdc:Bounds height="80.0" width="100.00000000000003" x="229.9708609547486" y="138.0"></omgdc:Bounds>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape bpmnElement="teacherPass" id="BPMNShape_teacherPass">
        <omgdc:Bounds height="80.0" width="99.99999999999994" x="436.9446358140222" y="138.0"></omgdc:Bounds>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape bpmnElement="judgeTask" id="BPMNShape_judgeTask">
        <omgdc:Bounds height="40.0" width="40.0" x="645.0" y="158.0"></omgdc:Bounds>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape bpmnElement="end" id="BPMNShape_end">
        <omgdc:Bounds height="28.0" width="28.0" x="795.0" y="164.0"></omgdc:Bounds>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape bpmnElement="principalPass" id="BPMNShape_principalPass">
        <omgdc:Bounds height="80.0" width="100.0" x="615.0" y="280.0"></omgdc:Bounds>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNEdge bpmnElement="judgeLess" id="BPMNEdge_judgeLess">
        <omgdi:waypoint x="684.5095911949685" y="178.43356643356645"></omgdi:waypoint>
        <omgdi:waypoint x="795.0000829380081" y="178.04860604497966"></omgdi:waypoint>
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge bpmnElement="principalNotPassFlow" id="BPMNEdge_principalNotPassFlow">
        <omgdi:waypoint x="615.0" y="320.0"></omgdi:waypoint>
        <omgdi:waypoint x="279.9708609547486" y="320.0"></omgdi:waypoint>
        <omgdi:waypoint x="279.9708609547486" y="217.95000000000002"></omgdi:waypoint>
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge bpmnElement="judgeMore" id="BPMNEdge_judgeMore">
        <omgdi:waypoint x="665.4326241134752" y="197.51043586109145"></omgdi:waypoint>
        <omgdi:waypoint x="665.1411660777385" y="280.0"></omgdi:waypoint>
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge bpmnElement="teacherNotPassFlow" id="BPMNEdge_teacherNotPassFlow">
        <omgdi:waypoint x="486.9446358140222" y="138.0"></omgdi:waypoint>
        <omgdi:waypoint x="486.9446358140222" y="98.8874737106014"></omgdi:waypoint>
        <omgdi:waypoint x="279.9708609547486" y="98.8874737106014"></omgdi:waypoint>
        <omgdi:waypoint x="279.9708609547486" y="138.0"></omgdi:waypoint>
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge bpmnElement="principalCheck" id="BPMNEdge_principalCheck">
        <omgdi:waypoint x="714.9499999999886" y="319.64664310954066"></omgdi:waypoint>
        <omgdi:waypoint x="806.5" y="319.0"></omgdi:waypoint>
        <omgdi:waypoint x="808.7518112709728" y="191.94785201600882"></omgdi:waypoint>
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge bpmnElement="applyFlow" id="BPMNEdge_applyFlow">
        <omgdi:waypoint x="329.9208609546613" y="178.0"></omgdi:waypoint>
        <omgdi:waypoint x="436.9446358140222" y="178.0"></omgdi:waypoint>
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge bpmnElement="teacherPassFlow" id="BPMNEdge_teacherPassFlow">
        <omgdi:waypoint x="536.8946358140222" y="178.0"></omgdi:waypoint>
        <omgdi:waypoint x="645.0" y="178.0"></omgdi:waypoint>
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge bpmnElement="startFlow" id="BPMNEdge_startFlow">
        <omgdi:waypoint x="129.94999932842546" y="178.0"></omgdi:waypoint>
        <omgdi:waypoint x="229.970860954748" y="178.0"></omgdi:waypoint>
      </bpmndi:BPMNEdge>
    </bpmndi:BPMNPlane>
  </bpmndi:BPMNDiagram>
</definitions>

将xml保存为生请假流程.bpmn20.xml复制到项目resources/processes目录下，如果没有processes文件夹就自己创建一个，Flowable会自动部署processes目录下的流程模型。启动项目后可以通过RepositoryService查询已经部署的模型，若查询结果不为空就代表模型部署成功了。

    @Autowired
    private RepositoryService repositoryService;

    @GetMapping
    public List<String> list() {
        List<ProcessDefinition> processList = repositoryService.createProcessDefinitionQuery().list();
        return processList.stream().map(ProcessDefinition::getName).collect(Collectors.toList());
    }

3. 测试流程

@SpringBootTest
@RunWith(SpringRunner.class)
public class StudentLeaveTest {

    @Autowired
    private RuntimeService runtimeService;

    @Autowired
    private TaskService taskService;

    @Autowired
    private HistoryService historyService;

    @Test
    public void test() {

        // 发起请假
        Map<String, Object> map = new HashMap<>();
        map.put("day", 2);
        map.put("studentUser", "小明");
        ProcessInstance studentLeave = runtimeService.startProcessInstanceByKey("StudentLeave", map);
        Task task = taskService.createTaskQuery().processInstanceId(studentLeave.getId()).singleResult();
        taskService.complete(task.getId());

        // 老师审批
        List<Task> teacherTaskList = taskService.createTaskQuery().taskCandidateGroup("teacher").list();
        Map<String, Object> teacherMap = new HashMap<>();
        teacherMap.put("outcome", "通过");
        for (Task teacherTask : teacherTaskList) {
            taskService.complete(teacherTask.getId(), teacherMap);
        }

        // 校长审批
        List<Task> principalTaskList = taskService.createTaskQuery().taskCandidateGroup("principal").list();
        Map<String, Object> principalMap = new HashMap<>();
        principalMap.put("outcome", "通过");
        for (Task principalTask : principalTaskList) {
            taskService.complete(principalTask.getId(), principalMap);
        }

        // 查看历史
        List<HistoricActivityInstance> activities = historyService.createHistoricActivityInstanceQuery()
                .processInstanceId(studentLeave.getId())
                .finished()
                .orderByHistoricActivityInstanceEndTime().asc()
                .list();
        for (HistoricActivityInstance activity : activities) {
            System.out.println(activity.getActivityName());
        }

    }

}

打印结果：

开始
流程开始
请假申请
申请流程
老师审批
通过
判断是否大于2天
小于2天
结束

将请假日期day改为5，打印结果：

开始
流程开始
请假申请
申请流程
老师审批
通过
判断是否大于2天
大于2天
校长审批
通过
结束

三、附录

1. 数据表说明

Flowable的所有数据库表都以ACT_开头。第二部分是说明表用途的两字符标示符。服务API的命名也大略符合这个规则。

• ACT_RE_* ：’ RE ’表示repository（存储）。RepositoryService接口操作的表。带此前缀的表包含的是静态信息，如，流程定义，流程的资源（图片，规则等）。
• ACT_RU_* ：’ RU ’表示runtime。这是运行时的表存储着流程变量，用户任务，变量，职责（job）等运行时的数据。flowable只存储实例执行期间的运行时数据，当流程实例结束时，将删除这些记录。这就保证了这些运行时的表小且快。
• ACT_ID_* : ’ ID ’表示identity(组织机构)。这些表包含标识的信息，如用户，用户组，等等。
• ACT_HI_* : ’ HI ’表示history。就是这些表包含着历史的相关数据，如结束的流程实例，变量，任务，等等。
• ACT_GE_* : 普通数据，各种情况都使用的数据。

原文地址